考虑人群-结构-环境耦合作用缆索式人行桥随机振动疲劳性能研究

Cable supported footbridges spring up in urban overpasses and tourist attractions due to its beautiful design, reasonable structure stress and good economic performance. Nature frequency of this type of footbridges is closer to the step frequency of pedestrian so that the cable produces greater fatigue stress under the crowd load, together with rugged environment, the mutual coupling of corrosiveness and fatigue stress often causes fatigue failure of cable supported footbridges. Since the crowd, structure and environment compose a complex dynamic system of multi scale and multi physical fields, and the research of random vibration of suspension bridge becomes a pioneering and interdisciplinary research topic. Based on the results of field test and theoretical analysis, a three-dimensional pedestrian dynamic model is established by the dynamic converse problem. The coupled vibration equation of the crowd-structure is established, in which the footbridge is simulated by the modified finite element model, and the pedestrian flow is simulated by the social force. Then, probability model of corrosion fatigue performance carve of suspension bridge is established according to fatigue test and finite element analysis. Taking crowd parameters, fatigue performance carves constant, fatigue stress and cycle number as random variables, fatigue limit state function of footbridge is deduced, and after discussing the influence of relevant parameters on the fatigue performance of pedestrian bridge, the obtained results are mutually checked with the results of the field monitoring. The research on the random vibration fatigue performance of the pedestrian cable supported footbridges is carried out based on the crowd-structure coupled effect, which can provide scientific basis for the detection, repair and maintenance of footbridges.

缆索式人行桥因造型美观、受力合理及经济性好等特点，在城市、景区及山区中得到广泛应用。此类结构自振频率与行人步频较为接近，在人群荷载作用下缆索产生较大疲劳应力，加之所处环境恶劣，环境腐蚀作用与疲劳应力互相耦合，常造成人行桥缆索疲劳破环。人群-结构-环境组成一个多尺度多物理场的复杂动力系统，人行桥随机振动疲劳研究成为多学科交叉的前沿课题。根据现场试验与理论分析结果，由动力学反问题建立三维行人动力学模型；采用修正后有限元模型模拟人行桥，利用社会力模型模拟行人流，建立人群-结构耦合振动方程；通过疲劳试验和有限元仿真，建立缆索腐蚀疲劳性能曲线概率模型。以人群参数、疲劳性能曲线常数、疲劳应力及循环次数为随机变量，建立人行桥疲劳极限状态函数，探讨相关参数对人行桥疲劳性能的影响，与现场监测结果相互校核。开展考虑人群-结构-环境耦合作用缆索式人行桥随机振动疲劳性能研究，为人行桥检测、修复及维护提供科技支撑。

人行悬索桥因受力合理、跨越能力强及经济性能好等特点，在峡谷、深水湖泊、城市立交和旅游景区中得到广泛应用。人行悬索桥自振频率较低，易于行人步频接近而产生共振疲劳。此外，人行桥所处自然环境恶劣，腐蚀作用与疲劳应力互相耦合，形成更为严重的腐蚀疲劳。具体成果如下：1）基于大量实测数据建立了单自由度行人生物力学模型，并对现有的单人步行荷载竖向动力模型比较了各个模型的使用特点，以及改进了双足行走倒立摆模型。2）针对人群运动导致人行结构振动多过大而日益突出的疲劳破坏问题，可供参考的研究成果甚少。以钢-玻璃人行桥为试验平台开展关于安装TMD前后人致人行桥疲劳性能的研究。通过长期应变监测数据，分析得出了该结构下的疲劳应力谱以及日平均损伤度，进而预估其疲劳寿命。3）在实验室环境下利用已制作的钢-玻璃人行桥结构模型，分析了基于行人-结构相互作用耦合系统动力参数的时变规律，给出了行人-结构耦合系统动力参数随人群、温度等非荷载因素的变化规律；以某体育馆悬挑楼盖为分析对象，通过数值仿真和现场测试研究了幕墙的约束刚度对楼盖振动模态的影响。4）采用提出的激励-传播-感知全路径结构人致振动舒适度评估框架对结构进行了评估，该评估方法分别考虑了结构和感知者的动力响应，评估结果较现有方法更为合理。5）在现有减振控制措施的基础上，提出了通过设置障碍物与TMD组合的人行结构混合减振策略，研究了人群荷载作用下设置障碍物对连廊的减振控制。对人行桥、大跨楼盖等工程结构进行人致振动舒适度评估并利用TMD对楼盖过量振动进行控制。6）针对现有结构振动测试中布置有线传感器带来的局限性，采用计算机视觉技术识别结构振动，所提出的方法相较于传统视觉监测方法，在保证精度要求的前提下提高了运算速度及鲁棒性，且无需人造靶标，具有一定的工程应用价值。该方法为桥梁结构损伤提供了非接触式的识别方法。